Career at Hogwarts

At an unknown point in her life, Vector accepted a teaching position at Hogwarts School. She became the Professor of Arithmancy, being given Classroom 7A on the seventh floor of Hogwarts Castle to teach her lessons in, and presumably an office elsewhere on the school grounds. Her relationship with the rest of the staff is unknown, though she was considered very strict and old-fashioned by some of her students, so she may have been like Minerva McGonagall in personality.

1991-1992 school year

Professor Vector worked at Hogwarts School of Witchcraft and Wizardry in the early 1990s and was present at the Sorting of Harry Potter and his classmates.

In the 1991 Start-of-Term Feast, she sat next to Keeper of Keys and Grounds, Rubeus Hagrid. She listened attentively to fellow Professor Minerva McGonagall, who was telling the first-years how the Sorting ceremony would proceed. She also witnessed as Harry Potter was sorted into [Gryffindor House. Professor Vector attended the first Quidditch match of the school term. She seemed to be cheerful after witnessing the victory of Gryffindor.

1993-1994 school year

"I heard [Hermione] talking to Professor Vector, that Arithmancy witch, this morning. They were going on about yesterday's lesson, but Hermione can't've been there, because she was with us in Care of Magical Creatures!"

In 1993, Hermione Granger began studying Arithmancy with Professor Vector and excelled in the class. After one lesson, they had a talk about their lesson the following day, which Ronald Weasley overheard, and was confused, as Hermione had Care of Magical Creatures the day before, and so could not have been in Arithmancy. In reality, she had been using a Time-Turner to get to all her lessons.

Also that year, a ginger girl, roommate of Hermione and best friend of Fay Dunbar, took her subject as well. However, unlike her, she found it hard, and confided in Hermione that it was too difficult for her.

1994-1995 school year

Hermione: "Lots of homework? Professor Vector didn't give us any at all."

On September 1st, 1994, the first day of the 1994-1995 school year, Professor Vector did not give her fourth year students any homework, an unusual occurrence, which Hermione Granger mentioned after Ronald Weasley told her that he had had a lot of homework. She was also presumably present for the arrival of the Triwizard Tournament participants, the Yule Ball and the memorial feast for Cedric Diggory.

1995-1996 school year

Professor Vector was once again teaching at Hogwarts in 1995, where she was present at the Start-of-Term Feast. When the new DADA teacher, Dolores Umbridge, interrupted Dumbledore to give a speech, Professor Vector and her colleagues were stunned at her audacity. Like her student Hermione Granger, Professor Vector and the other teachers understood the true gravity of the speech (the Ministry was interfering at Hogwarts) and did not clap when Umbridge finished her speech. Professor Umbridge was later appointed High Inquisitor with powers to inspect and dismiss teachers she felt were not up to scratch (or rather, those that were loyal to Dumbledore). Professor Vector's classes were presumably inspected, but she likely proved to be a competent teacher as she was not dismissed or put on probation.

When Rubeus Hagrid returned from a mission given to him by Headmaster Dumbledore, he had a conversation with Harry Potter, Ron Weasley, and Hermione Granger, Professor Vector walked past them and was almost knocked off her feet by Hagrid. As she was passing them and they were entering the Entrance Hall, she had presumably come downstairs to the Great Hall to eat.

Also that year, one boy told someone that he was unsure if he wanted to do Arithmancy because of Professor Vector's strict demeanour[5].

Later in the year, Umbridge became Headmistress after Dumbledore was ousted from Hogwarts, but Professor Vector and her fellow staff members did nothing to help her and instead found means of annoying or hindering her. Indeed, when fireworks went berserk all over the place and a corridor was turned into a swamp (both times courtesy of the Weasley twins), Professor Vector did not attempt to remove either obstacle and took great pleasure in having the Headmistress run all over the castle getting rid of escaped fireworks in the classrooms. When Hogwarts was restored to normalcy and Umbridge was ousted and pursued from the premises by Peeves, Professor Vector and the other teachers did nothing to halt the students from chasing after her.

1996-1997 school year

"Hermione[...] dashed off to see Professor Vector about a mistake she thought she might have made in her last Arithmancy essay."

Later life

Physical appearance

Professor Vector was a witch with long, thin black hair with a fair skin colour. She often wore red robes with a matching pointed hat.

Personality and traits

Professor Vector was described as very strict by a student who was not sure if he should take her lessons.[5] She was also said to have given out masses of complicated homework to her students, who were all third years or over, though appeared to be rather sociable with the other teachers. It is possible that she either supported the Gryffindor Quidditch team or was simply unbiased, as she was visibly shocked when Harry Potter lost control of his broom, and when Angelina Johnson was "attacked".

Etymology

Septima most likely comes directly from Latin Septima which translates to "the seventh" (female form). As seven is the most powerful magical number, and Arithmancy deals with the numbers appearing in magic, this name suits the character well. A "vector" is a concept in physics and mathematics, specifying a quantity that has both magnitude and direction, and represented by an arrow.

In LEGO Harry Potter: Years 1-4, Septima's character token can be found in the Tom Riddle's diary level. This may indicate she already worked at Hogwarts in the 1940s. Other characters' tokens can be found in matching places, i.e. Minerva McGonagall in the Transfiguration classroom; however, there is another possibility that Septima's token location has no particular meaning.

Professor Vector's first name only appeared on a list of the Hogwarts professors which was released on J. K. Rowling's website.

Originally, she was a male named Septimus and her last name was intended to be Vecta.[7]